I use Proton Mail, which lets you make 'aliases', which you can use for different sites. The alias forward staright to your main (or a nominated) email.
You can use https://simplelogin.io/ to do the same, and I'm sure there are similar services around.
E.g. I can't have feckwhatsapp@feckfacebook.com as my WhatsApp email, and it would forward to whatever account I normally use.
I do this for pretty much everything on line, so they all have their own bespoke email for me.
As a complete noob who installed Mint about two weeks ago, I have Thoughts™. This is a good start, I think., and I'm really glad to see it, but it still makes some assumptions and misses a couple of things I came across that I think would be helpful.
I'll try to find some time tomorrow to pull together some edits and suggestions to share, rather than a bunch of comments here.
How's best to share them back?